[ska]

I think it really depends.

I've seen big sector contracts (e.g. 10k-100k employees) with it built in for a fixed number of years. Presumably the negotiators talked through some indicators originally.

I've also seen several 'eh, on average it's about 2%" type giving leading to a 2% written into your comp.

I've also seen places give it but not in your contract; based on execs opinion I guess on what real cost-of-living was doing. I suppose that's plausibly as accurate as picking an index.

[Qworg]

I've seen inflation adjustments, but cost of living adjustments are far more common.

[ska]

The two concepts are so intertwined they are often rolled together.

FWIW I've seen contracts with separate clauses (e.g. something like everyone gets 2%, if you live in this city or this city you also get a 5% col adjustment). The non-inflation aspect of c-o-l changes is usual housing related and regional, I think (or based on remoteness)